[PATCH] D139679: [X86] Don't zero out %eax if both %al and %ah are used

[Bill Wendling via Phabricator via llvm-commits]

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The iterator over super and sub registers doesn't include both 8-bit
registers in its list. So if both registers are used and only one of
them is live on return, then we need to make sure that the other 8-bit
register is also marked as live and not zeroed out.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D139679

Files:
  llvm/lib/Target/X86/X86FrameLowering.cpp
  llvm/test/CodeGen/X86/zero-call-used-regs-i386.ll

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